PHD THESIS TITLE: HOLISTIC MANAGEMENT OF ELECTRIC SUPPLY SECURITY IN LIBERALIZED MARKETS ABSTRACT The final use of electric energy is constituted in an essential component on modern life. Thus, electric supply problems are potentially expensive and traumatic. Nevertheless, electric supply systems cannot get total supply security due to prohibitive costs caused by uncontrollable and unregulated system variables. Until now, traditional management of electric supply security in liberalized markets (recognized for being fragmented and biased) is based on its consideration as a positive externality and public good. However, the mechanisms and actions foreseen to ensure long-term electric supply have neither been efficient nor effective. So, reduction of storing tendencies and electric supply failures have emerged as consequences of this problematic, creating elevated costs in competitive electric markets along with social, economical and political turmoil. Therefore, this thesis proffer a paradigm change on the conception of electric supply security into a process and service of common usage, which involves the restatement of PDCA cycle (Plan-Do-Check-Act) in search for holistic management. The historical information from the Spanish Electric Production Market was used to validate this approach. Conclusively, active participation and commitment of all interested parts was found to be a requisite for an efficient providing and transaction of electric supply security in liberalized markets. Moreover, this service must be prioritized to design a sustainable electric supply system which could provide demand with affordable prices and uninterrupted availability. To achieve it, strategies applied to demand response resources and efficiency are effective for medium and long term electric supply assurance. KEY WORDS Liberalized electric markets, centralized and decentralized energy resources, common-pool resources, electric supply security, process management.